The present invention relates to a rotary mower of the type which has two supports or cutter bars connected to one another, and fitted with a set of rotary blade carriers of an oval shape or the like, which are driven by gear trains disposed therebelow.
The cutting width of this type of mower is generally restricted to seven or eight rotary blade carriers fitted onto a support or cutter bar which is formed in a single piece. This is due in particular to the fact that it is difficult to transmit a significant amount of power from one end of a support or cutter bar, in view of the small volume allotted to the transmission units, which are housed below the rotary blade carriers. Moreover, the smaller the length of the support or cutter bar, the more easily is it able to follow any unevenness of the terrain.
Consequently, when it is desired to produce a rotary mower, which has more than eight rotary blade carriers, for example, in the form of discs, it is advantageous to arrange several supports or cutter bars in an end-to-end manner. When this arrangement is adopted, it is preferable to drive the blade carriers of each support or cutter bar separately, preferably on one end of each support, by means of flexible drive devices, such as belts. The belts, which may be either notched or smooth are, in fact, likely to slip in the event of any excess loads, thereby protecting the drive devices.
Since a machine of the type described above is required to cut crops uniformly over its whole cutting width, care should be taken to ensure that no portions or strips of the crop are left uncut, especially in the region between two supports or cutter bars connected to one another end-to-end. Consequently, two neighboring supports or cutter bars have to be connected by arranging them quite close to one another. However, since the cutting unit supports or blade carriers of each bar are driven by means of belts, and since, in certain parts of their trajectory, the oval-shaped blade carriers are offset by 90.degree. in relation to one another along the whole width of the machine, which is formed by an assembly of the supports or bars, the blade carriers of one bar or another may become blocked when encountering an obstacle such as, for example, a boundary post in a field. The belts which drive the blade carriers of each support or bar are able to absorb such blocking. However, if the blade carriers of a support or cutter bar are blocked, the relative angular position of one set of blade carriers is altered in relation to the angular position of the set of blade carriers of the neighboring support or cutter bar. This means, that, at certain points in their trajectory, the major axis of the ovally-shaped blade carriers of one support or cutter bar are no longer offset by 90.degree. in relation to the major axis of the ovally-shaped blade carriers of the neighboring support or cutter bar.
Moreover, if the distance between all the shafts of the blade carriers is constant over the whole width of the machine, and since the blade carriers are oval in shape, neighboring blade carriers of different cutter bars or supports may collide. Such a collision may not only damage the blade carriers, but also the bearings onto which they are fitted, thus possibly necessitating time-consuming and costly repairs and, in any event, a prolonged period of idleness of the machine.